The Effect of Molecular Weight on Hyaluronan’s Cartilage Lubricating Ability – Alone and in Combination with Proteoglycan

INTRODUCTION: Hyaluronan (HA), a primary constituent of synovial fluid (SF), is an important contributor to the boundary lubrication of articular cartilage. Indeed, high molecular weight (MW) HA, ~800 kDa, has been shown to function effectively as a cartilage boundary lubricant in a dose dependant manner, and act synergistically with Proteoglycan 4 (PRG4, a mucin-like glycoprotein also found in SF that contributes to boundary lubrication in a dose-dependent manner) to lower friction, through an unknown mechanism, to levels near that of SF. It is currently not known if MW affects HA’s cartilage boundary lubricating ability alone, or the poorly understood HA+PRG4 interaction that synergistically lowers friction at the cartilage surface. Thus, the objectives of this study were to 1) assess the MW dependence of HA’s cartilage boundary lubricating ability, +/PRG4, at physiological concentrations, and 2) examine the HA-PRG4 interaction in solution.